/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.coders;



import com.bff.gaia.unified.sdk.util.VarInt;

import com.bff.gaia.unified.sdk.values.TypeDescriptor;



import java.io.*;



/**

 * A {@link Coder} that encodes {@link Integer Integers} using between 1 and 5 bytes. Negative

 * numbers always take 5 bytes, so {@link BigEndianIntegerCoder} may be preferable for integers that

 * are known to often be large or negative.

 */

public class VarIntCoder extends AtomicCoder<Integer> {



  public static VarIntCoder of() {

    return INSTANCE;

  }



  /////////////////////////////////////////////////////////////////////////////



  private static final VarIntCoder INSTANCE = new VarIntCoder();

  private static final TypeDescriptor<Integer> TYPE_DESCRIPTOR = new TypeDescriptor<Integer>() {};



  private VarIntCoder() {}



  @Override

  public void encode(Integer value, OutputStream outStream) throws IOException, CoderException {

    if (value == null) {

      throw new CoderException("cannot encode a null Integer");

    }

    VarInt.encode(value, outStream);

  }



  @Override

  public Integer decode(InputStream inStream) throws IOException, CoderException {

    try {

      return VarInt.decodeInt(inStream);

    } catch (EOFException | UTFDataFormatException exn) {

      // These exceptions correspond to decoding problems, so change

      // what kind of exception they're branded as.

      throw new CoderException(exn);

    }

  }



  @Override

  public void verifyDeterministic() {}



  /**

   * {@inheritDoc}

   *

   * @return {@code true}. {@link VarIntCoder} is injective.

   */

  @Override

  public boolean consistentWithEquals() {

    return true;

  }



  /**

   * {@inheritDoc}

   *

   * @return {@code true}. {@link #getEncodedElementByteSize} is cheap.

   */

  @Override

  public boolean isRegisterByteSizeObserverCheap(Integer value) {

    return true;

  }



  @Override

  public TypeDescriptor<Integer> getEncodedTypeDescriptor() {

    return TYPE_DESCRIPTOR;

  }



  @Override

  protected long getEncodedElementByteSize(Integer value) throws Exception {

    if (value == null) {

      throw new CoderException("cannot encode a null Integer");

    }

    return VarInt.getLength(value.longValue());

  }

}